CLASS IV. 147 



shcner than the calyx and coriaceous: rudiments opposite, senile, v e- 

 sembling valves : nectary lateral. (ribbon-grass.) 



C. Spikdlets many-flowered. 



PO'A. Spikelets oblong or linear, compressed, many-flowered ; ca- 

 Jyx shorter than the florets: corolla herbaceous, awnless, often araci> 

 aoid at the base; lower valve scarious at the margin. (spear-grass.) 



Exotic. 



SORG"HUM. Florets in pairs, one perfect, with a 3-valved corolla, 

 and sessile ; the other staminate or neutral, and pedicelled. (broom 

 corn.) 



DAC^'TITLIS. Spikelets aggregated in unilateral heads, many flower- 

 ed: calyx shorter than the florets, with one large glume, keeled, point 

 ed: corolla with the lower valve keeled, emarginate, mucronate.- 

 (orchard grass.) 



AVE'NA. Calyx 2-valved; 2,3, or many flowered: corolla valves 

 mostly bearded at the base, lower one torn, with a twisted awn on the 

 back: glumes membranaceous, and somewhat follicle-like; seed 

 coated. (oats.) 

 mm D. Flowers in spikes. 



TRI'TICUM. Calyx 2-valved, about 3-flowered ; florets sessile on the 

 teeth of the rachis, obtusish and pointed ; glumes beardless, or inter- 

 ruptedly bearded. (wheat.) 



SECA'I.E. Calyx 2-valved, 2 or 3-flowered : spikelets sessile on the 

 teeth of the rachis, with the terminal floret abortive: glumes subulate, 

 opposite, shorter than the florets : corolla with the lower valve lung:- 

 awned. (rye.) 



CLASS iv. TETRANORIA. Four Stamens. 



Order 1. Monogynia. One pistil. 



A. Flowers superior. 



(l-petaled.) 



CEPHALAN"THUS. Inflorescence in a head: general calyx none, 

 proper calyx superior, minute, angular, 4-cleft: corolla funnel-form: 

 receptacle globular, hairy : seed solitary, oblong. (button-bush.) 



HOUSTO'NIA. Calyx half superior, 4-toothed: corolla salver-form, 

 4-cleft ; capsule 2-celled, many-seeded, opening transversely. (inno- 

 cence.) 



(4-petaled.) 



COR"NUS. Calyx 4-toothed: drupe with a 2-celled nut Some spe- 

 cies have a 4-leaved involucrurn. (dogwood, false box.) 



Southern. 



LY'CIUM. Corolla tubular, having the throat closed by the beards of 

 the filaments: stamens often 5: berry 2-celled ; many seeded. (mat- 

 rimony.) 



